Patent Document 1 shown as a known apparatus discloses one in which a current is made smaller than normal, that is, an assist is limited to be small to continue control at an abnormal time when a disconnection has occurred in one phase of a motor of an electric power steering apparatus. This reduces torque pulsation generated by an abnormality; and consequently, a feeling of physical disorder that a driver feels can be reduced. Furthermore, Patent Document 2 discloses one in which the size of an assist is limited to be smaller than normal to continue control and is not rapidly reduced, but is gradually limited to be small in a stepwise fashion by multiplying a constant not higher than 1 to a normal assist gain in the case where a slight abnormality is generated at a part of an electric power steering apparatus body. This makes possible to reduce a feeling of physical disorder that a driver feels because there is no rapid change.
Patent Document 1: Japanese Unexamined Patent Publication No. 10-181617
Patent Document 2: Japanese Unexamined Patent Publication No. 2003-170857
Patent Document 3: Japanese Examined Patent Publication No. 3600805